Adjuvant radiotherapy versus observation following gross total resection for atypical meningioma: a systematic review and meta-analysis

A Case-based Guide for World Health Organization (WHO) Grade 2 Meningioma Radiosurgery and Radiation Therapy from The Radiosurgery Society

PURPOSE

Meningiomas represent the most common primary tumor of the central nervous system. Current treatment options include surgical resection with or without adjuvant radiation therapy (RT), definitive RT, and observation. However, the radiation dose, fractionation, and margins used to treat patients with WHO grade 2 meningiomas, which account for approximately 20% of all meningiomas, are not clearly defined, and deciding on the optimal treatment modality can be challenging owing to the lack of randomized data.

METHODS AND MATERIALS

In this manuscript, 3 cases of patients with WHO grade 2 meningiomas are presented with descriptions of treatment options after gross total resection, subtotal resection, and previous irradiation. Treatment recommendations were compiled from 9 central nervous system radiation oncology and neurosurgery experts from The Radiosurgery Society, and the consensus of treatment recommendations is reported.

RESULTS

Both conventional and stereotactic RT are treatment options for WHO grade 2 meningiomas. The majority of prospective data in the setting of WHO grade 2 meningiomas involve larger margins. Stereotactic radiosurgery/hypofractionated stereotactic RT are less appropriate in this setting. Conventionally fractionated RT to at least 59.4 Gy is considered standard of care with utilization of preoperative and postoperative imaging to evaluate the extent of disease and possible osseous involvement. After careful discussion, stereotactic radiosurgery/hypofractionated stereotactic RT may play a role for the subset of patients who are unable to tolerate the standard lengthy conventionally fractionated treatment course, for those with prior RT, or for small residual tumors. However, more studies are needed to determine the optimal approach.

CONCLUSIONS

This case-based evaluation of the current literature seeks to provide examples for the management of grade 2 meningiomas and give examples of both conventional and stereotactic RT.

The Impact of Social Determinants on Receipt of Adjuvant Radiation Nationally Following Atypical Meningioma Surgery

OBJECTIVE

We aimed to identify socioeconomic gaps in the administration of adjuvant radiotherapy (RT) for patients with atypical meningioma (AM) and secondarily to determine differences in survival between patients receiving radiation and those not receiving radiation at 12 and 60 months.

METHODS

The National Cancer Database was queried for patients receiving AM surgery between 2004 and 2019. Statistical analyses were performed to assess the association between receipt of adjuvant radiation and social determinants. Secondarily, Kaplan-Meir curves were used to compare overall patient survival between those that received radiation and those that did not.

RESULTS

Adjuvant radiation was less likely to be administered to patients over 65 (95% confidence interval [CI] = 0.53-22 0.77) and more likely to be administered to males (95% CI = 1.07-1.38). Compared to the Southern USA, patients were more likely to receive RT in the Northeastern (95% CI 24 = 1.40-2.05), Midwestern (95% CI = 1.06-1.54), and Western parts of the USA (95% 25 CI = 1.31-2.00). Patients residing furthest from their facility were less likely to receive radiation (95% CI = 0.65-0.98). Insured patients were more likely to receive radiation (P = 0.048) than uninsured patients. On multivariate analysis, no differences were found between racial groups regarding adjuvant radiation. For patients unstratified, radiation was shown to improve survival at 12 and 60 months.

CONCLUSIONS

Disparities exist in the administration of adjuvant RT for AM. Patients over 65, women, those residing in the Southern USA, those living further from their facilities and uninsured patients are less likely to receive radiation than their counterparts.

Initial management of newly diagnosed WHO grade 2-3 adult meningioma following surgery: results from the Dutch Brain Tumour Registry (2016-2021)

PURPOSE

Meningiomas classified as grade 2-3 according to the World Health Organisation (WHO) require combined surgery and in most cases radiotherapy (RT). Their initial management was evaluated using the Dutch Brain Tumour Registry.

METHODS

The study included 393 patients aged ≥ 18 years with newly diagnosed meningioma WHO grade 2-3 between 2016 and 2021. Factors associated with adjuvant RT < 6 months following surgery were identified using logistic regression analyses, thereby accounting for variation between CNS regional tumour boards through mixed-effect modelling. This variation was further assessed by funnel plots for case-mix adjusted ratios of RT across tumour boards. The association with patients' survival at 5 years was evaluated with inverse probability-weighted accelerated failure (Weibull) models. Analyses were performed on multiple imputed datasets (m = 10) to account for missing data.

RESULTS

Adjuvant RT was administered to 22.2% (59/266) of patients with WHO grade 2 meningioma following a total resection, to 61.1% (58/95) following a partial resection, and to 68.8% (22/32) of patients with WHO grade 3 meningioma (61.5% after partial and 73.7% after total resection). RT was associated with grade 3, partial resection, bone invasion, and absence of multiple lesions. Management varied across tumour boards for grade 2 meningioma following total resection. Adjuvant RT was associated with survival benefit in case of grade 3 disease (hazard ratio: 0.40, 95%-confidence interval: 0.16-0.95, p = 0.04).

CONCLUSION

This national review revealed variation across CNS regional tumour boards in the management of grade 2 meningioma following total resection, and demonstrated survival benefit of adjuvant RT in grade 3 meningioma.

Surgery alone versus surgery plus adjuvant radiotherapy for WHO grade 2 meningioma: meta-analysis of reconstructed time-to-event data

INTRODUCTION

WHO Grade 2 meningiomas present diagnostic and management challenges. Surgery, particularly gross total resection (GTR), is crucial, often followed by adjuvant radiotherapy (RT); however, there are clinical equipoise and ongoing randomized trials of RT after GTR.

METHODS

This systematic review evaluates the efficacy of gross total resection (GTR) and GTR plus adjuvant radiotherapy (RT) for WHO grade 2 meningiomas, adhering to PRISMA guidelines. It excludes irrelevant studies, conducts a thorough search until January 2024, and specifically analyzes overall survival (OS) and progression-free survival (PFS) outcomes for WHO grade 2 meningiomas. Statistical analysis adopts a two-stage approach with the R package "IPDfromKM," and quality assessment is conducted using the ROBINS-I tool.

RESULTS

In our analysis of 23 studies involving 3822 WHO grade 2 meningioma patients, GTR + RT resulted in a significantly longer PFS (HR: 0.849, 95% CI: 0.730 to 0.988, p = 0.035) compared to GTR alone. Although OS trended better with GTR + RT (HR: 0.79, 95% CI: 0.57 to 1.11, p = 0.173), the difference was not statistically significant, suggesting the need for further investigation.

CONCLUSION

Our study reveals a benefit to adjuvant RT for improving PFS for WHO grade 2 meningiomas. Integrating molecular characteristics into treatment strategies will refine the management of these tumors in the future.

Unveiling an atypical meningioma amidst stroke symptoms: importance of accurate diagnosis and comprehensive follow-up: A case report

Meningiomas are common brain tumors that are classified as either benign, atypical, or malignant. This case involves a 75-year-old woman with a medical history of ischemic heart disease, hypertension, and diabetes. She was diagnosed with an atypical meningioma while being evaluated for symptoms related to a stroke. Upon her presentation at the hospital, the patient displayed symptoms such as loss of motor function on the right side of her body, weakness, dysphagia, and aphasia, indicating a possible stroke. Imaging tests confirmed both the stroke symptoms and the presence of an atypical meningioma. The primary focus of her treatment was addressing the stroke symptoms. Despite being asymptomatic for the meningioma, the patient opted for conservative treatment and declined invasive procedures. Her decision was respected, and a plan was put in place for regular monitoring and counseling regarding the meningioma. This case emphasizes the significance of tailored treatment decisions in complicated clinical situations involving incidental brain tumors.

[Ga68] DOTATATE PET/MRI-guided radiosurgical treatment planning and response assessment in meningiomas

BACKGROUND

Our purpose was to determine the utility of [68Ga]-DOTATATE PET/MRI in meningioma response assessment following radiosurgery.

METHODS

Patients with meningioma prospectively underwent postoperative DOTATATE PET/MRI. Co-registered PET and gadolinium-enhanced T1-weighted MRI were employed for radiosurgery planning. Follow-up DOTATATE PET/MRI was performed at 6-12 months post-radiosurgery. Maximum absolute standardized uptake value (SUV) and SUV ratio (SUVRSSS) referencing superior sagittal sinus (SSS) blood pool were obtained. Size change was determined by Response Assessment in Neuro-Oncology (RANO) criteria. Association of SUVRSSS change magnitude and progression-free survival (PFS) was evaluated using Cox regression.

RESULTS

Twenty-seven patients with 64 tumors (26% World Health Organization [WHO]-1, 41% WHO-2, 26% WHO-3, and 7% WHO-unknown) were prospectively followed post stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT; mean dose: 30 Gy, modal dose 35 Gy, mean of 5 fractions). Post-irradiation SUV and SUVRSSS decreased by 37.4% and 44.4%, respectively (P < .0001). Size product decreased by 8.9%, thus failing to reach the 25% significance threshold as determined by RANO guidelines. Mean follow-up time was 26 months (range: 6-44). Overall mean PFS was 83% and 100%/100%/54% in WHO-1/-2/-3 subcohorts, respectively, at 34 months. At maximum follow-up (42-44 months), PFS was 100%/83%/54% in WHO-1/-2/-3 subcohorts, respectively. Cox regression analyses revealed a hazard ratio of 0.48 for 10-unit reduction in SUVRSSS in the SRS cohort.

CONCLUSIONS

DOTATATE PET SUV and SUVRSSS demonstrated marked, significant decrease post-radiosurgery. Lesion size decrease was statistically significant; however, it was not clinically significant by RANO criteria. DOTATATE PET/MR thus represents a promising imaging biomarker for response assessment in meningiomas treated with radiosurgery.

CLINICALTRIALS.GOV IDENTIFIER

NCT04081701.

Paired Primary and Recurrent Rhabdoid Meningiomas: Cytogenetic Alterations, BAP1 Gene Expression Profile and Patient Outcome

Rhabdoid meningiomas (RM) are a rare meningioma subtype with a heterogeneous clinical course which is more frequently associated with recurrence, even among tumors undergoing-complete surgical removal. Here, we retrospectively analyzed the clinical-histopathological and cytogenetic features of 29 tumors, from patients with recurrent (seven primary and 14 recurrent tumors) vs. non-recurrent RM (n = 8). Recurrent RM showed one (29%), two (29%) or three (42%) recurrences. BAP1 loss of expression was found in one third of all RM at diagnosis and increased to 100% in subsequent tumor recurrences. Despite both recurrent and non-recurrent RM shared chromosome 22 losses, non-recurrent tumors more frequently displayed extensive losses of chromosome 19p (62%) and/or 19q (50%), together with gains of chromosomes 20 and 21 (38%, respectively), whereas recurrent RM (at diagnosis) displayed more complex genotypic profiles with extensive losses of chromosomes 1p, 14q, 18p, 18q (67% each) and 21p (50%), together with focal gains at chromosome 17q22 (67%). Compared to paired primary tumors, recurrent RM samples revealed additional losses at chromosomes 16q and 19p (50% each), together with gains at chromosomes 1q and 17q in most recurrent tumors (67%, each). All deceased recurrent RM patients corresponded to women with chromosome 17q gains, although no statistical significant differences were found vs. the other RM patients.

Scalp metastasis from atypical meningioma: A case report and literature review

Key Clinical Message

Scalp metastasis from atypical meningioma, though rare, underscores the importance of meticulous surgical techniques to prevent tumor cell implantation. Early detection and comprehensive management, including surgery and adjuvant therapy, are crucial for optimal outcomes.

Abstract

Meningiomas are tumors of the meninges that originate in the arachnoid layer from arachnoid cap cells. Atypical meningiomas, classified as WHO grade 2 tumors, tend to metastasize and recur if not surgically managed properly. Scalp metastasis is a rare occurrence that presents as a subcutaneous elevation. A 33-year-old patient presented with a complaint of a constant, dull pressure headache persisting for the past 12 months, exacerbated by exertion, along with seizures and neuropsychiatric symptoms. The patient had no significant medical history but had undergone surgery 4 years ago for a WHO grade 2 meningioma. The current brain MRI revealed a dural tail sign, along with masses on both the left and right sides of the frontal lobe, extending to involve the skin on the forehead and scalp. The patient underwent surgical resection and adjuvant radiation therapy. At the 12-month follow-up, no neurological deterioration or tumor recurrence was observed. A literature review on scalp metastasis in patients with atypical meningioma was also conducted, including eight articles published up to September 2023. The mechanism of metastasis development appears to be consistent in all eight reported cases, involving the implantation of tumor cells during resection. Therefore, there is a critical need for meticulous intra- and post-operative surgical techniques to prevent such implantation.

Reconstruction of Moderately and Severely Atrophic Scalp-A Multicentric Experience in Surgical Treatment of Patients Irradiated for Tinea Capitis in Childhood and Surgical Algorithm

Background and Objectives: Before the introduction of griseofluvin, the use of X-ray radiation was the treatment of choice for tinea capitis. More than half a century later various types of tumors have been found to be associated with childhood irradiation due to tinea capitis, most commonly cancers of the head and neck, as well as brain tumors. The often unusually aggressive and recurrent nature of these tumors necessitates the need for repeated surgeries, while the atrophic skin with an impaired vascular supply due to radiation often poses an additional challenge for defect reconstruction. We present our experience in the surgical treatment of such patients. Materials and Methods: This is a retrospective cohort study. In this study, 37 patients treated for acquired defects of the scalp with a history of irradiation therapy due to tinea capitis in childhood were included in this study, 24 male and 13 female patients. The mean age at the first appointment was 60.6 ± 7.8, with the youngest included patient being 46 and the oldest being 75 years old. Patients' characteristics, surgical treatment, and complications were analyzed and a reconstructive algorithm was developed. Results: Local flaps were used for reconstruction in 34 patients, direct sutures were used in 10 patients and 20 patients received split-thickness skin grafts for coverage of both primary and secondary defects for reconstruction of flap donor sites. One regional flap and one dermal substitute covered by an autologous skin graft were also used for reconstruction. Complications occurred in 43.2% of patients and were significantly associated with the presence of comorbidities (p = 0.001), aseptic bone necrosis (p = 0.001), as well as skin atrophy in frontal, occipital, and parietal region (p = 0.001, p = 0.042 and p = 0.001, respectively). A significant correlation between major complications and moderate skin atrophy was found only in the parietal region (p = 0.026). Conclusions: Unfortunately, many protocols developed for scalp reconstruction are not applicable in the setting of severe or diffuse scalp skin atrophy associated with high tumor recurrence rate and radiation-induced vascular impairment, such as in tinea capitis patients in Serbia. An algorithm has been developed based on the authors' experience in managing these patients.

Novel Postoperative Serum Biomarkers in Atypical Meningiomas: A Multicenter Study

BACKGROUND

There has been no known serum biomarker to predict the prognosis of atypical meningioma.

OBJECTIVE

To investigate the prognostic impact of serum biomarkers in patients newly diagnosed with resected intracranial atypical meningiomas.

METHODS

This study enrolled 523 patients with atypical meningioma who underwent surgical resection between 1998 and 2018 from 5 Asian institutions. Serum laboratory data within 1 week after surgery were obtained for analysis. Optimal cutoffs were calculated for each serum marker using the maxstat package of R.

RESULTS

Of 523 patients, 19.5% underwent subtotal resection and 29.8% were treated with adjuvant radiation therapy (ART). Among the 523 patients, 454 were included in the multivariate analysis for the progression/recurrence (P/R) rate excluding patients with incomplete histopathologic or laboratory data. On multivariate analysis, tumor size >5 cm, subtotal resection, and postoperative aspartate aminotransferase/alanine transaminase (De Ritis) ratio >2 were associated with higher P/R rates, whereas ART and postoperative platelet count >137 × 10 3 /μL were associated with lower P/R rates. In the subgroup of patients treated with ART, tumor size >5 cm and postoperative neutrophil-to-lymphocyte ratio >21 were associated with higher P/R rates. By contrast, postoperative De Ritis ratio >2 remained an adverse prognosticator in patients not treated with ART.

CONCLUSION

Postoperative De Ritis ratio, platelet count, and neutrophil-to-lymphocyte ratio were revealed as a novel serum prognosticator in newly diagnosed atypical meningiomas. Additional studies are warranted to validate its clinical significance and biological background.

Interdisciplinary Therapeutic Approaches to Atypical and Malignant Meningiomas

Meningiomas have the highest incidence among brain tumors. In contrast to benign tumors that constitute the majority of this tumor entity, the treatment of aggressive meningiomas (WHO Grade 2 and 3) is more challenging, requiring gross total removal of the tumor and the affected dura and adjuvant radiotherapy. Sometimes the location and/or the configuration of the tumor do not favor radical surgical resection without endangering the patient's clinical condition after surgery and pharmacological therapy has, until now, not been proven to be a reliable alternative. Discussion: In this narrative review, we discuss the current literature with respect to the management of meningiomas, discussing the importance of the grade of resection in the overall prognosis of the patient and in the planning of adjuvant therapy. Conclusions: According to the location and size of the tumor, radical resection should be taken into consideration. In patients with aggressive meningiomas, adjuvant radiotherapy should be performed after surgery. In cases of skull base meningiomas, a maximal, though safe, resection should take place before adjuvant therapy. An interdisciplinary approach is beneficial for patients with primary or recurrent meningioma.

Intracranial meningiomas: an update of the 2021 World Health Organization classifications and review of management with a focus on radiation therapy

Meningiomas account for approximately one third of all primary intracranial tumors. Arising from the cells of the arachnoid mater, these neoplasms are found along meningeal surfaces within the calvarium and spinal canal. Many are discovered incidentally, and most are idiopathic, although risk factors associated with meningioma development include age, sex, prior radiation exposure, and familial genetic diseases. The World Health Organization grading system is based on histologic criteria, and are as follows: grade 1 meningiomas, a benign subtype; grade 2 meningiomas, which are of intermediately aggressive behavior and usually manifest histologic atypia; and grade 3, which demonstrate aggressive malignant behavior. Management is heavily dependent on tumor location, grade, and symptomatology. While many imaging-defined low grade appearing meningiomas are suitable for observation with serial imaging, others require aggressive management with surgery and adjuvant radiotherapy. For patients needing intervention, surgery is the optimal definitive approach with adjuvant radiation therapy guided by extent of resection, tumor grade, and location in addition to patient specific factors such as life expectancy. For grade 1 lesions, radiation can also be used as a monotherapy in the form of stereotactic radiosurgery or standard fractionated radiation therapy depending on tumor size, anatomic location, and proximity to dose-limiting organs at risk. Optimal management is paramount because of the generally long life-expectancy of patients with meningioma and the morbidity that can arise from tumor growth and recurrence as well as therapy itself.

Clinical Efficacy of Adjuvant Radiotherapy for World Health Organization Grade II Intracranial Meningioma

BACKGROUND

Maximal surgical resection remains the treatment of choice for grade II meningiomas, and for some authors it is sufficient to guarantee a long indolent course even without postsurgical radiotherapy (RT), but there is no consensus on the use of RT in this patient population.

METHODS

We retrospectively compared clinical and radiologic outcomes between World Health Organization grade I (group A) and grade II (group B) surgically treated meningiomas, focusing on the role of adjuvant RT. We registered clinical, surgical, and radiologic data to detect differences in survival and functional outcome between the 2 groups.

RESULTS

The final cohort consisted of 284 patients for group A and 94 patients for group B. Group B showed a higher risk of developing recurrence independently of the extent of resection (7.75% for Group A vs. 27.7% for Group B, P = 0.01). Patients who did not undergo adjuvant RT documented recurrence in 50% of cases, compared with 19% of patients who underwent RT (P = 0.024). There is a weak difference in the risk of developing postoperative seizures in the group submitted to radiotherapy (P = 0.08). Performance status remained stable for both groups, but for Group B it tended to decrease significantly after 1 year with regard to extent of resection and RT.

CONCLUSIONS

Recurrence is more frequent for grade II meningiomas, even though there are no significant differences in terms of complications and functional outcome. Radiotherapy in grade II meningiomas does indeed lead to better control of recurrence but leads to an increased risk of seizures and reduced performance status.

Long Term Outcome and Quality of Life of Intracranial Meningioma Patients Treated with Pencil Beam Scanning Proton Therapy

The aim of this study was to assess the clinical outcome, including QoL, of patients with intracranial meningiomas WHO grade 1-3 who were treated with Pencil Beam Scanning Proton Therapy (PBS PT) between 1997 and 2022. Two hundred patients (median age 50.4 years, 70% WHO grade 1) were analyzed. Acute and late side effects were classified according to CTCAE version 5.0. Time to event data were calculated. QoL was assessed descriptively by the EORTC-QLQ-C30 and BN20 questionnaires. With a median follow-up of 65 months (range: 3.8-260.8 months) the 5 year OS was 95.7% and 81.8% for WHO grade 1 and grade 2/3, respectively (p < 0.001). Twenty (10%) local failures were observed. Failures occurred significantly (p < 0.001) more frequent in WHO grade 2 or 3 meningioma (WHO grade 1: n = 7, WHO grade 2/3: n = 13), in patients with multiple meningiomas (p = 0.005), in male patients (p = 0.005), and when PT was initiated not as upfront therapy (p = 0.011). There were no high-grade toxicities in the majority (n = 176; 88%) of patients. QoL was assessed for 83 (41.5%) patients and for those patients PT did not impacted QoL negatively during the follow-up. In summary, we observed very few local recurrences of meningiomas after PBS PT, a stable QoL, and a low rate of high-grade toxicity.

Radiotherapy and radiosurgery for meningiomas

Meningiomas comprise a histologically and clinically diverse set of tumors arising from the meningothelial lining of the central nervous system. In the past decade, remarkable progress has been made in deciphering the biology of these common neoplasms. Nevertheless, effective systemic or molecular therapies for meningiomas remain elusive and are active areas of preclinical and clinical investigation. Thus, standard treatment modalities for meningiomas are limited to maximal safe resection, radiotherapy, or radiosurgery. This review examines the history, clinical rationale, and future directions of radiotherapy and radiosurgery as integral and effective treatments for meningiomas.

Neurocognitive considerations in the treatment of meningioma with radiation therapy: applications for quantitative neuroimaging and precision radiation medicine

This article focuses on the role of radiotherapy in the management of meningioma, in the definitive and adjuvant setting and across the spectrum of meningioma grade. Treatment paradigms, informed by clinical evidence, are discussed. Notably, we focus on the impact of radiotherapy on normal brain tissues and neurocognitive function, particularly the dose-dependent changes in white matter and cerebral cortex thickness. Novel imaging techniques have allowed the identification of microstructural changes to eloquent white matter, cortex, and subcortical regions as biomarkers for understanding RT-induced changes in cognitive functioning. Deficits in multiple domains including attention, memory, language and executive function can become more pronounced following radiation. Longitudinal assessment with imaging and neurocognitive testing pre- and post-radiation have allowed correlation between dose to specific regions of the brain and decline in associated domains of neurocognitive function. These findings suggest incorporation of areas at higher risk for neurocognitive sequelae into precision radiation planning. Volumetric arc therapy, advanced planning with cortical sparing, proton therapy and stereotactic radiosurgery are reviewed as options for delivering therapeutic dose to target volumes while minimizing risk to adjacent sensitive regions. The treatment of meningioma is an evolving area, with improving outcomes for higher grade disease in modern trials, where care must be taken to maximize both disease control as well as quality of life for patients.

NF2 mutations are associated with resistance to radiation therapy for grade 2 and grade 3 recurrent meningiomas

PURPOSE

High grade meningiomas have a prognosis characterized by elevated recurrence rates and radiation resistance. Recent work has highlighted the importance of genomics in meningioma prognostication. This study aimed to assess the relationship between the most common meningioma genomic alteration (NF2) and response to postoperative radiation therapy (RT).

METHODS

From an institutional tissue bank, grade 2 and 3 recurrent meningiomas with both > 30 days of post-surgical follow-up and linked targeted next-generation sequencing were identified. Time to radiographic recurrence was determined with retrospective review. The adjusted hazard of recurrence was estimated using Cox-regression for patients treated with postoperative RT stratified by NF2 mutational status.

RESULTS

Of 53 atypical and anaplastic meningiomas (29 NF2 wild-type, 24 NF2 mutant), 19 patients underwent postoperative RT. When stratified by NF2 wild-type, postoperative RT in NF2 wild-type patients was associated with a 78% reduction in the risk of recurrence (HR 0.216; 95%CI 0.068-0.682; p = 0.009). When stratified by NF2 mutation, there was a non-significant increase in the risk of recurrence for NF2 mutant patients who received postoperative RT compared to those who did not (HR 2.43; 95%CI 0.88-6.73, p = 0.087).

CONCLUSION

This study demonstrated a protective effect of postoperative RT in NF2 wild-type patients with recurrent high grade meningiomas. Further, postoperative RT may be associated with no improvement and perhaps an accelerated time to recurrence in NF2 mutant tumors. These differences in recurrence rates provide evidence that NF2 may be a valuable prognostic marker in treatment decisions regarding postoperative RT. Further prospective studies are needed to validate this relationship.

Clinical Management of Supratentorial Non-Skull Base Meningiomas

Supratentorial non-skull base meningiomas are the most common primary central nervous system tumor subtype. An understanding of their pathophysiology, imaging characteristics, and clinical management options will prove of substantial value to the multi-disciplinary team which may be involved in their care. Extensive review of the broad literature on the topic is conducted. Narrowing the scope to meningiomas located in the supratentorial non-skull base anatomic location highlights nuances specific to this tumor subtype. Advances in our understanding of the natural history of the disease and how findings from both molecular pathology and neuroimaging have impacted our understanding are discussed. Clinical management and the rationale underlying specific approaches including observation, surgery, radiation, and investigational systemic therapies is covered in detail. Future directions for probable advances in the near and intermediate term are reviewed.

Radiotherapy for meningiomas

Meningiomas are the most common primary central nervous system neoplasm. Despite promising recent progress in elucidating the genomic landscape and underlying biology of these histologically, molecularly, and clinically diverse tumors, the mainstays of meningioma treatment remain maximal safe resection and radiation therapy. The aim of this review of meningioma radiotherapy is to provide a concise summary of the history, current evidence, and future for application of radiotherapy in meningioma treatment.

Long-Term Follow-Up, Treatment Strategies, Functional Outcome, and Health-Related Quality of Life after Surgery for WHO Grade 2 and 3 Intracranial Meningiomas

Simple Summary

Meningiomas are the most common group of primary intracranial tumors. While the majority are classified as WHO grade 1, WHO grade 2 and 3 meningiomas have poorer outcomes, even after gross total resection, and often require supplementary treatment. Long-term follow-up data regarding the progression-free survival (PFS) and overall survival (OS) for grade 2 and 3 tumors are scarce, and data evaluating the routine use of supplementary radiotherapy and radiosurgery have been inconclusive. Furthermore, few studies have reported data on the health-related quality of life (HRQoL), anxiety, and depression for these patients. In this population-based cohort study, we reviewed 51 cases of WHO grade 2 and 3 meningiomas. We found that the median OS was 13 years for grade 2 and 1.4 years for grade 3 meningiomas. Meningioma was the cause of death in 93% of the patients who passed away. The surviving patients showed HRQoL measures comparable to that of the general population, with the exception of significantly more anxiety and depression. All patients who worked preoperatively returned to work after their treatment.

Abstract

Progression-free survival (PFS) and overall survival (OS) for WHO grade 2 and 3 intracranial meningiomas are poorly described, and long-term results and data evaluating the routine use of supplementary fractionated radiotherapy (RT) or stereotactic radiosurgery (SRS) has been inconclusive. The aim of this study was to determine the long-term PFS and OS at a center that does not employ routine adjuvant RT. For this purpose, a retrospective population-based cohort study was conducted of all WHO grade 2 and 3 meningiomas surgically treated between 2005 and 2013. The cohort was uniformly defined according to the WHO 2007 criteria to allow comparisons to previously published reports. Patient records were reviewed, and patients were then prospectively contacted for structured quality-of-life assessments. In total, 51 consecutive patients were included, of whom 43 were WHO grade 2 and 8 were grade 3. A Simpson grade 1–2 resection was achieved in 62%. The median PFS was 31 months for grade 2 tumors, and 3.4 months for grade 3. The median OS was 13 years for grade 2, and 1.4 years for grade 3. The MIB-1-index was significantly associated with an increased risk for recurrence (p = 0.018, OR 1.12). The median PFS was significantly shorter for high-risk tumors compared to the low-risk group (10 vs. 46 months; p = 0.018). The surviving meningioma patients showed HRQoL measures comparable to that of the general population, with the exception of significantly more anxiety and depression. All patients who worked before surgery returned to work after their treatment. In conclusion, we confirm dismal prognoses in patients with grade 2 and 3 meningiomas, with tumor-related deaths resulting in severely reduced OS. However, the cohort was heterogenous, and a large subgroup of both grade 2 and 3 meningiomas was alive at 10 years follow-up, suggesting that a cure is possible. In addition, fractionated radiotherapy and chemotherapy had little benefit when introduced for recurrent and progressive diseases.

Should adjuvant radiotherapy be used in atypical meningioma (WHO grade 2) following gross total resection? A systematic review and Meta-analysis

BACKGROUND

The role of adjuvant radiotherapy (RT) following gross total resection (GTR) in atypical meningioma (AM) is not well established and its benefit remains unclear. We aim to evaluate the survival benefit of adjuvant RT in AM following GTR.

METHODS

We searched biomedical databases for studies published between January 1964-February 2021 and included studies reporting primary outcomes of 5-year PFS, 5-year OS and had survival curves for restricted mean survival time (RMST) calculations. Data extracted from survival curves were pooled and analyzed using a random-effects model. Hazard ratio (HR) was calculated for sensitivity analysis.

RESULTS

We included 12 non-randomized studies comprising 1,078 patients. 803 (74.5%) patients were treated with GTR alone and 275 (25.5%) patients received adjuvant RT. In 9 studies, RT included 3 D conformal RT, intensity modulated RT, or fractionated stereotactic radiotherapy); in 3 studies, stereotactic radiosurgery was also used. Median dose of RT was 59.4 Gy. Adjuvant RT resulted in an increase of 3.9 months for restricted mean PFS truncated at 5 years (95% CI 0.23-7.72; p = 0.037) and a 22% reduction in the hazard of disease progression or death (hazards ratio 0.78; 95% CI 0.46-1.33; p = 0.370). Restricted mean OS, truncated at 5 years, was improved with adjuvant RT by 1.1 months (95% CI 0.37-1.81; p = 0.003) and a 21% reduction in the hazard of death from any cause (HR 0.79; 95% CI 0.51-1.24; p = 0.310). Meta-regression analysis of the RMST of EBRT dose did not reveal any significant difference in PFS or OS between studies reporting median dose of <59.4 Gy vs. ≥ 59.4 Gy.

CONCLUSION

Adjuvant RT following GTR in patients with AM improved restricted mean PFS and OS. While we await the results from ongoing randomized controlled trials, adjuvant RT should be recommended.

Discrimination between microcystic meningioma and atypical meningioma using whole-lesion apparent diffusion coefficient histogram analysis

AIM

To explore the value of whole-lesion apparent diffusion coefficient (ADC) histogram analysis in discriminating microcystic meningioma (MCM) from atypical meningioma (AM).

MATERIALS AND METHODS

Clinical and preoperative MRI data of 20 patients with MCM and 26 patients with AM were analysed retrospectively. Whole-lesion apparent diffusion coefficient (ADC) histogram analysis was performed on each patient's lesion to obtain histogram parameters, including mean, variance, skewness, kurtosis, the 1st (ADCp1), 10th (ADCp10), 50th (ADCp50), 90th (ADCp90), and 99th (ADCp99) percentiles of ADC. The differences between the ADC histogram parameters of the two tumours were compared, and the receiver operating characteristic (ROC) curve was used to assess the diagnostic performance of statistically significant parameters in distinguishing the two tumours.

RESULTS

The mean, ADCp1, ADCp10, ADCp50, and ADCp90 of MCM were greater than those of AM, and significant differences were observed in these parameters between MCM and AM (all p<0.05). ROC analysis showed that the mean had the highest area under the curve value (AUC) in distinguishing the two tumours (AUC = 0.852), when using 120.46 × 10^-6 mm²/s as the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for discriminating the two groups were 84.6%, 75%, 80.4%, 81.5%, and 78.9%, respectively.

CONCLUSION

Histogram analysis based on whole-lesion ADC maps was useful for discriminating between MCM from AM preoperatively, with the mean being the most promising potential parameter.

Role of diffusion-weighted imaging in differentiating angiomatous meningioma from atypical meningioma

BACKGROUND

Conventional magnetic resonance imaging (MRI) characteristics of angiomatous meningioma (AM) and atypical meningioma (ATM) sometimes overlap. However, there are significant differences in the treatment and prognosis of the two tumors. The aim of the study was to assess the role of diffusion-weighted imaging (DWI) in differentiating AM from ATM.

METHODS

Clinical, MRI, and pathological data of 25 patients with AM and 30 patients with ATM were retrospectively analyzed. Main clinical indexes, conventional MRI characteristics, and apparent diffusion coefficient (ADC) values were compared between the two groups, and receiver operating characteristic (ROC) curves were drawn to determine the diagnostic performance of ADC values in distinguishing AM from ATM.

RESULTS

The minimum ADC value (ADCmin), average ADC value (ADCmean), and relative ADC value (rADC) for AM (908.00 ± 117.00 × 10^-6 mm²/s, 921.04 ± 67.09 × 10^-6 mm²/s, and 1.15 ± 0.09, respectively) were significantly higher than those for ATM (710.50 ± 79.80 × 10^-6 mm²/s, 748.50 ± 67.27 × 10^-6 mm²/s, and 0.96 ± 0.09, respectively; all P < 0.05). ROC analysis showed that ADCmin had the best diagnostic performance in distinguishing AM from ATM, with an area under the curve value of 0.977. When using 759.00 × 10^-6 mm²/s as the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 90.00 %, 96.00 %, 92.72 %, 96.40 %, and 88.90 %, respectively.

CONCLUSIONS

DWI plays an important role in differentiating AM from ATM, and ADCmin is the most promising potential parameter that can improve the preoperative diagnostic accuracy of both tumors.

Adjuvant Radiotherapy Versus Surveillance for Grade 2 Intracranial Meningiomas: A Multi-Institutional Propensity Score-Matched Study

Purpose

We aimed to compare the outcomes of adjuvant radiotherapy (ART) and surveillance in patients with grade 2 meningiomas (MNG2) who underwent surgical resection.

Materials and Methods

Data from four hospitals, in which patients aged ≥18 years underwent Simpson grade 1−4 surgical resection for newly diagnosed MNG2 between 1998 and 2018, were examined in this multicenter retrospective cohort study. Patients receiving ART with conventional fractionation were compared with those undergoing surveillance. Progression-free survival (PFS), progression/recurrence (P/R) were evaluated.

Results

This study included 518 patients, 158 of whom received ART. The median follow-up duration was 64.9 months. In the total cohort, ART was independently associated with significantly improved PFS (HR, 0.35; 95% CI, 0.23–0.55; P<0.001) and P/R (HR, 0.30; 95% CI, 0.18–0.48; P<0.001). In the propensity score-matched cohort (n=143 in each group), the 5-year PFS rates were 80.8% and 57.7% (P=0.004), and the 5-year P/R rates were 16.5% and 40.0% (P=0.002) in the ART and surveillance groups, respectively. After gross total resection, the 5-year PFS (85.0% vs. 64.7%; P=0.020) and P/R rates (15.2% vs. 32.0%; P=0.035) were significantly better in the ART group than in the surveillance group. A model for P/R was developed using recursive partitioning analysis with surgical extent, tumor size, and Ki-67 index. ART reduced the risk of P/R in the low- (P=0.069), intermediate- (P=0.044), and high-risk groups (P<0.001). Local control was also significantly enhanced by ART among all the risk groups (all P<0.05).

Conclusions

ART significantly improved PFS and P/R in patients with MNG2, irrespective of the surgical extent, and can be recommended after gross total resection. A prognostic model may guide decision-making for the use of ART.

Risk Stratification to Define the Role of Radiotherapy for Benign and Atypical Meningioma: A Recursive Partitioning Analysis

BACKGROUND

The role of adjuvant radiotherapy (RT) for benign or atypical meningioma is controversial.

OBJECTIVE

To identify prognostic factors and a subgroup that could be potentially indicated for adjuvant RT.

METHODS

A total of 336 patients with benign and 157 patients with atypical meningioma underwent surgical resection between January 2015 and December 2019. We retrospectively analyzed 407 patients who did not receive adjuvant RT to stratify risk groups for recurrence. A recursive partitioning analysis (RPA) with the prognostic factors for their failure-free survival (FFS) divided the patients into risk groups.

RESULTS

The 3-year FFS with surgical resection only was 76.5%. Identified prognostic factors for FFS were skull base location, tumor size, brain invasion, a Ki-67 proliferation index of ≥5%, and subtotal resection. The RPA-classified patients were divided into 4 risk groups: very low, low, intermediate, and high, and their 3-year FFS were 98.9%, 78.5%, 59.8%, and 34.2%, respectively. Intermediate-risk and high-risk groups comprise the patients with meningioma of sizes ≥2 cm after subtotal resection or meningioma of sizes >3 cm, located in the skull base or with brain invasion, respectively. After combining with patients treated with adjuvant RT, no FFS benefit was found in the very low-risk and low-risk groups after adjuvant RT, whereas significantly improved FFS was found in the intermediate-risk and high-risk groups (P < .05).

CONCLUSION

The RPA classification revealed a subgroup of patients who could be potentially indicated for adjuvant RT even after gross total resection or for whom adjuvant RT could be deferred.

Histopathological predictors of progression-free survival in atypical meningioma: a single-center retrospective cohort and meta-analysis

To determine the prognostic significance of histopathological features included in the diagnostic criteria of atypical meningioma for progression-free survival (PFS). We performed a retrospective cohort study and meta-analysis. Brain invasion, mitotic index, spontaneous necrosis, sheeting, prominent nucleoli, high cellularity, and small cells were the histopathological features of interest. The data from 25 studies involving 3590 patients including our cohort (n = 262) were included. The pooled HR of mitotic index at a cutoff value of 4 showed no statical significance in the gross analysis (pooled HR, 1.09; 95% CI 0.61-1.96; p = 0.7699). Furthermore, it failed to prognosticate PFS in other pooled analyses. For brain invasion, no consistent association with the progression was found in each pooled analysis according to the included studies. Among the remaining five atypical features, spontaneous necrosis, sheeting, and prominent nucleoli showed a significant correlation with PFS in the gross analysis. In the analysis that pooled the HRs from the multivariate analyses, only spontaneous necrosis had significant association with PFS. The available evidence supports that the current cutoff value of mitotic index for diagnosing atypical meningioma might be improper to have prognostic value. The prognostic significance of brain invasion also needs further evaluation.

Radiation therapy for atypical and anaplastic meningiomas: an overview of current results and controversial issues

Meningiomas are the most common intracranial tumors. Most meningiomas are WHO grade 1 tumors whereas less than one-quarter of all meningiomas are classified as atypical (WHO grade 2) and anaplastic (WHO grade 3) tumors, based on local invasiveness and cellular features of atypia. Surgical resection remains the cornerstone of meningioma therapy and represents the definitive treatment for the majority of patients; however, grade 2 and grade 3 meningiomas display more aggressive behavior and are difficult to treat. Several retrospective series have shown the efficacy and safety of postoperative adjuvant external beam radiation therapy (RT) for patients with atypical and anaplastic meningiomas. More recently, two phase II prospective trials by the Radiation Therapy Oncology Group (RTOG 0539) and the European Organisation for Research and Treatment of Cancer (EORTC 2042) have confirmed the potential benefits of fractionated RT for patients with intermediate and high-risk meningiomas; however, several issues remain a matter of debate. Controversial topics include the timing of radiation treatment in patients with totally resected atypical meningiomas, the optimal radiation technique, dose and fractionation, and treatment planning/target delineation. Ongoing randomized trials are evaluating the efficacy of early adjuvant RT over observation in patients undergoing gross total resection.

Adjuvant radiotherapy in grossly total resected grade II atypical meningiomas. A protective effect on recurrence? A systematic review and meta-analysis

INTRODUCTION

Management of grade II Atypical Meningiomas (AM) remains controversial. Conflicting evidences exist on the possible protective effect of adjuvant radiotherapy (ART) on recurrence in grossly resected AMs. The aim of this meta-analysis is to evaluate the role of ART in grossly resected (Simpson grades 1-3) AMs on the recurrence and survival.

EVIDENCE ACQUISITION

Data were retrieved from comparative studies of AMs undergone surgical resection alone vs. surgery+ART. Only grossly total resected AMs (Simpson grade 1,2,3) were included. The individual and pooled odds ratio (OR) for the crude recurrence, progression free survival (PFS) at 1, 3 and 5-years, as well as for the overall survival (OS) at 5-years were calculated by using the Mantel-Haenszel model in surgery alone vs. surgery+ART.

EVIDENCE SYNTHESIS

11 studies were considered eligible. 8 were included for the outcome "crude recurrence"; 6 for PFS at 1-3 years, 7 for PFS at 5-years; 6 for the OS at 5-years. Results suggest that surgery+ART might have a protective role on recurrence in gross-totally resected AMs (OR:1.66). Specifically, surgery+ART slightly improved PFS at 1-year (OR:0.92) and more consistently at 3- and 5-years (OR:0.31 and 0.35 respectively) hence favoring a combined approach.

CONCLUSIONS

Current literature on the impact of ART after gross total resection of AM are still heterogeneous and not systematically reported. The present meta-analysis suggests a possible protective role of postoperative RT against long-term recurrence as compared to surgical resection alone.